Stereoselective Synthesis of Differentially Protected Derivatives of the Higher Amino Sugars Destomic Acid and Lincosamine from Serine and Threonine
作者:James A. Marshall、Serge Beaudoin
DOI:10.1021/jo9517914
日期:1996.1.1
The aminoheptose destomic acid (3.5) and the aminooctose lincosamine (6.8) were synthesized in protected form by parallel sequences starting from the oxazolidine derivatives 2.4 and 5.1 of N-CBz serinal and N-BOC threoninal. The parallel sequences feature BF(3)-promoted addition of the (R)-gamma-OTBS allylic stannane 2.8 to the homologated enals 2.7 and 5.4, respectively, followed by stereoselective
通过从N-CBz丝氨酸和N-BOC苏氨酸的恶唑烷衍生物2.4和5.1开始的平行序列,以受保护的形式合成了氨基庚糖脱氢氨基酸(3.5)和氨基八糖林可胺(6.8)。平行序列的特征是将(R)-γ-OTBS烯丙基锡烷2.8 BF(3)促进分别添加到同源的烯醛2.7和5.4中,然后对衍生的bis-OTBS醚2.10和5.6进行立体选择性双二羟基化。这些中间体的较少受阻碍的邻二醇部分的区域选择性氧化裂解分别导致了γ-内酯3.2和5.8。在前一种情况下,用TBAF处理并随后水解除去了OTBS和丙酮化物保护基团,得到了脱氢酸前体吡喃糖3.4。通过甲硅烷基醚裂解,将乳糖醇5.8转化为吡喃糖苷6.3,酸性水解,并生成双丙酮化物。C7羟基的反转是通过Mitsunobu方法对p-NO(2)C(6)H(4)CO(2)H进行的。随后水解,BOC基团的裂解和N-乙酰化得到林可胺衍生物6.7。